java.lang.Object | ||
↳ | org.apache.lucene.search.Collector | |
↳ | org.apache.lucene.search.TopDocsCollector<T extends org.apache.lucene.search.ScoreDoc> |
Known Direct Subclasses |
A base class for all collectors that return a TopDocs
output. This
collector allows easy extension by providing a single constructor which
accepts a PriorityQueue
as well as protected members for that
priority queue and a counter of the number of total hits.
Extending classes can override topDocs(int, int)
and
getTotalHits()
in order to provide their own implementation.
Fields | |||||||||||
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EMPTY_TOPDOCS | |||||||||||
pq | The priority queue which holds the top documents. | ||||||||||
totalHits | The total number of documents that the collector encountered. |
Protected Constructors | |||||||||||
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Public Methods | |||||||||||
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The total number of documents that matched this query.
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Returns the top docs that were collected by this collector.
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Returns the documents in the rage [start ..
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Returns the documents in the rage [start ..
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Protected Methods | |||||||||||
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Returns a
TopDocs instance containing the given results. | |||||||||||
Populates the results array with the ScoreDoc instaces.
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Inherited Methods | |||||||||||
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From class
org.apache.lucene.search.Collector
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From class
java.lang.Object
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The priority queue which holds the top documents. Note that different implementations of PriorityQueue give different meaning to 'top documents'. HitQueue for example aggregates the top scoring documents, while other PQ implementations may hold documents sorted by other criteria.
The total number of documents that the collector encountered.
The total number of documents that matched this query.
Returns the documents in the rage [start .. start+howMany) that were
collected by this collector. Note that if start >= pq.size(), an empty
TopDocs is returned, and if pq.size() - start < howMany, then only the
available documents in [start .. pq.size()) are returned.
This method is useful to call in case pagination of search results is
allowed by the search application, as well as it attempts to optimize the
memory used by allocating only as much as requested by howMany.
NOTE: you cannot call this method more than once for each search
execution. If you need to call it more than once, passing each time a
different range, you should call topDocs()
and work with the
returned TopDocs
object, which will contain all the results this
search execution collected.
Returns the documents in the rage [start .. pq.size()) that were collected
by this collector. Note that if start >= pq.size(), an empty TopDocs is
returned.
This method is convenient to call if the application always asks for the
last results, starting from the last 'page'.
NOTE: you cannot call this method more than once for each search
execution. If you need to call it more than once, passing each time a
different start
, you should call topDocs()
and work
with the returned TopDocs
object, which will contain all the
results this search execution collected.
Returns a TopDocs
instance containing the given results. If
results
is null it means there are no results to return,
either because there were 0 calls to collect() or because the arguments to
topDocs were invalid.
Populates the results array with the ScoreDoc instaces. This can be overridden in case a different ScoreDoc type should be returned.